Electric furnace.



UNITED STATES PATENT OFFICE.

ADOLPHE MINET AND ENRI' LOUIS noncn LUCAS, or PARIS, FRANCE.

ELECTRIC FURNACE.

Specification of Letters Patent.

Patented July 14, 1914.

Application filed December so, 1913. Serial No. 809,487.

To all whom it may] concern.

- Be it known that we, ADOLPHE MiNET, of

which the required temperature is generated.

This resistance is constituted by the combination ,of two resistances,viz., a principal resistance and a secondary resistance. The

former generates the greater portion of the heat set. up by Joule effectand is consti tuted by'a mass of granulated carbon which is maintainedin shape by the pressure of the secondaryresistance which restsupon 'it,so that the constancy of the values of the current (voltage andamperage) during the whole reaction is insured. The secondaryresistance, which ls'shunted relatively to the principal resistance, isconstituted by pieces or blocks of material which have a conductivityconsiderably less than that of the principal resistance so that only asmall part of the current passes through it. These blocks are heatedmainly by .thermal conductivity and distribute the heat, to the retortswhich are inclosed in suitably shaped cavities.

Another essential feature of the furnace is the electrodes each of whichconsists of a metal plate connected with the current is to prevent suchheating of the electrodes as woulchrendcr them practically useless.

The invention is illustrated in the ac companying drawings wh.ereinFigure 1 is a longitudinal section and Fig. 2 a transverseisection ofthe improved furnace.

a is the body of the furnace built of very refractory bricks covered by.plates b of similar refractory material.

c are walls dividing the interior of the furnace, made of carbonaceoussubstances through the resistances d 01 sufiiciently light that thepressure exerted by the walls shall not exceed 11.025 lbs.

per 15.5 square inches. The interior of the furnace is of a size justsuiiicient to conta1n the heat generating resistances and thedistillation retorts.

The resistances comprise two distinct elements, via, aprincipalresistance d and a' secondary resistance constituted by aplurality of elements (Z (Z (Z5. The principal resistance d isconstituted by a mass of granulated carbon of perfectly regulargeometrical configuration having the form of astraightprism rectangularin cross section. The constant pressure to which it is submitted owingto the fact that it supports the resistances d d ll and the retorts e e6, prevents it from changing shape. Its conductivity is such that it.receives 90 per cent. of the current which passes through the furnace.

The resistances (Z ...(Z are consti- .g ood conductors of heat but theirelectrical conductivity is ten times smaller than that of the resistance(Z, so that only ten percent. of the current passes through them. his tobe understood, however, that ninety and ten per cent. are not abs lutevalues but are values given by way of example only.

As only a small'quantity of current passes (i they generate only a smallamount. of heat by Joule efi'ect, but they transmit by thermalconductivity the heat generated by d,- this heat distributes itselfthroughout the mass of the resistances J, (Z d and, during the durationof the reaction, the temperatures' distributed within the furnace remainin perfect equilibrium.

"he retorts e 0 are similar to those usually employed in the metallurgyof Zinc and are provided with a condensation pocket f and a nozzle 9.Current is led to the principal resistance (Z by means of electrodeseach. of which comprises a metal sheet h (usually of steel) to which thecurrent leadthese conditions only a small amount of heat is generated inthe column 2' by Joule efi'ect. Owing to this arrangement, while thetemperature of the resistance d reaches from 1500 to 1600 degrees whenthe furnace is in terioration of adjustable electrodes.

, the current during the reaction, perfect ad- In addition to the.advantages above set forth (viz. continuous working and longduration,'invariability of the constants of justment and distribution ofthe temperature at different points within the furnace, indestructibleelectrodes and very high efliciency) the new furnace possesses numerousother advantages. For lnstance, owing to the fact that the interiorcapacity of the furoace'is just suflicient to containthe resist-- ancesand the retorts heat losses through the walls are reduced to a minimumand the thermal efiiciency is very high. The retorts c being surroundedby the blocks 1/, (Z cannot become subjected to excessive heat and theheat is evenly distributed around their periphery. As they aresupported, throughout their length. their thicknessmay notablydecreased, thus increasing their permeability to heat.

' In the construction illustrated the resistance d is constituted by asingle mass of carbon but when the furnace must have a It is also to beobserved that certain. width, it; might be constituted by a plurality ofparallel masses. Similarly, the

furnace may be constituted by a plurality of superposed floors.

Claims:

1. In an electric furnace, a principal resistance constituted by a massof granulated carbon, and a secondary resistance constituted by blocksless conductive thanthe car- 3. In an electric furnace, a principalresistance constituted by a mass of granulated carlmn, a secondaryresistance constituted by blocks less conductive than the carbon,exerting a pressure on the principal resistance and electrodesconstituted by large granules of carbon and metal plates.

4. In an electric furnace, a principal resistance constituted by a massof granulated carbon, a secondary resistance constituted by hollowblocks less conductive than the carbon, exerting a pressure on theprincipal resistance, retorts arranged in the hollow blocks, andelectrodes constituted by large granules of carbon and metal plates.

7 The foregoing specification of our improvements in electric furnacessigned by us this 19th day of December, 1918.

ADOLPHE MINET. HENRI LOUIS LEoNoE LUCAS.

Witnesses:

HANSON C. Coxn, Rem THIRIOT.

